V4L or Video4Linux is a core interface for supporting real-time capturing of analog video. V4L API works only with Linux systems, although the developers named it after V4W (Video for Windows).
The purpose of the V4L is to ease the way software engineers enable video support in the applications by standardizing the output of numerous analog TV tuners, MPEG decoders/encoders, video capture gadgets, streamers, and other similar devices.
A list of V4L supported devices also includes: video via PCI, graphics cards with TV tuner or capturing facilities, video via PCIe, video via USB, and other analog devices (webcams, scanners, radios, IEEE 1394 devices, etc.
V4L is compatible with FreeBSD (Video4BSD).